Project Abstract/Summary: This proposal describes a five-year mentored research and training plan that will facilitate the development of Dr. Thomas Raffay, MD to an independent investigator in neonatal pulmonary disease. Building upon Dr. Raffay's background as a clinical neonatologist and a basic scientist in airways reactivity and neonatal bronchopulmonary dysplasia (BPD), he will attain expertise in S-nitrosothiol biology, flow-cytometry, conditional transgenic animal models, pharmacology, and translational science through structured mentorship, rigorous hands-on laboratory experiences, didactics teaching, and formal classwork and skills training at Case Western Reserve University/Rainbow Babies and Children's Hospital, the Mayo Clinic Rochester, and the University of Windsor. Dr. Benjamin Gaston, a pioneer in S-nitrosothiol signaling in pediatric lung disease, and Dr. Richard J Martin, an international leader in neonatal airways disease and BPD, will provide their expertise and an established track record of mentorship to this project and Dr. Raffay's transition to research independence. In the United States, 14,000 new diagnoses of the pediatric lung disease, BPD, are made annually in surviving premature infants, with costs exceeding $2.5 billion. Treatment options are limited for the severe bronchospasms and life-long airway obstruction that characterize BPD. Using a neonatal hyperoxia mouse model of BPD and airways hyperreactivity, Dr. Raffay's new data identify a viable therapy. Treatment with a single aerosol of S-nitrosoglutathione (GSNO) reverses airways hyperresponsiveness in juvenile BPD mice and room air recovered adults. GSNO is a potent endogenous bronchodilator, critical for the airways diseases of asthma and cystic fibrosis. In this model, neonatal hyperoxia increases the catabolic breakdown of GSNO caused by increased expression and activity of the enzyme, S-nitrosoglutathione reductase (GSNOR), at least in part through hyperoxic downregulation of a microRNA (miR-342-3p). This study will test the overall hypothesis that loss or inhibition of GSNOR activity will protect against BPD airways hyperreactivity in juvenile and adult mice. This proposal will evaluate the effects of neonatal hyperoxia on BPD airways hyperreactivity and parenchymal lung remodeling utilizing global GSNOR knockout mice (Aim 1A); identify the lung tissues involved in GSNOR and miR-342-3p expression utilizing fluorescence-activated cell sorting and develop and test conditional GSNOR knockout mice (Aim 1B); test a pharmaceutical-grade GSNOR inhibitor drug in wild- type mice to alleviate acute bronchoconstriction (Aim 2a) and chronically to attenuate the BPD phenotype (Aim 2b). In a translational human aim (Aim 3): GSNOR levels, real-time fluorescent GSNO catabolism, and microRNA expression will be measured in human fetal airway smooth muscle exposed to hyperoxia; and GSNO and GSNOR inhibitors will be tested as a treatment for attenuation of oxygen induced hyper- contractility. These studies are clinically important because GSNOR inhibitors are currently in clinical trials for cystic fibrosis and asthma which could ultimately serve as a new treatment for bronchopulmonary dysplasia.